Pulse generator with magnetic inserts on rotor



June 28, 1966 E. M. SAWYER 3,258,551

PULSE GENERATOR WITH MAGNETIC INSERTS ON ROTOR Filed Sept. 25, 1963 2 Sheets-Sheet 1 Fig.1

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M0 62a I 62.6 62 62 26 INVENTOR.

ELBERT M. SAWVE/P BY RW ATTORNEY June 28, 1966 E. M. SAWYER PULSE GENERATOR WITH MAGNETIC INSERTS ON ROTOR Filed Sept. 25, 1963 2 Sheets-Sheet 2 INVENTOR. ELBER'T M. SAWVER BY W A TTORNE' V United States Patent Delaware Filed Sept. 25, 1963, Ser. No. 311,348 14 Claims. (Cl. 200-19) This invention relates to a magnetic pick-up, and more particularly to a magnetic pick-up type of distributor which can be used to control an internal combustion engine ignition system.

The present invention relates to an improved magnetic pick-up which can be used in an ignition system of the type shown in the Short et a1. patent, 3,087,001, and can be substituted for the magnetic pick-up shown in that patent.

One of the problems encountered in the design of magnetic pick-ups for controlling a semiconductor ignition system such as that shown in the above-mentioned Short et a1. patent is the generation of sufiicient voltage by the magnetic pick-up when the engine is being cranked at low speed such as is experienced in cold weather. Thus, the magnetic pick-up must control ignition timing both when the engine is operating at high speed and when it is being cranked by an electric starting motor at low speed and it is important that sufiicient voltage be developed at low cranking speed to properly control ignition timing.

It accordingly is one of the objects of this invention to provide a magnetic pick-up type of distributor which is capable of producing higher output voltages than those heretofore known.

Another object of this invention is to provide a magnetic pick-up wherein the working air gaps can be placed at a larger diameter than is normally possible. This means that with the same pole tip widths as have been used in previous magnetic pick-ups, the flux change will take place in a shorter period of time and a larger induced voltage will result.

Another object of this invention is to provide a magnetic pickup wherein it is possible to obtain a larger number of turns for the magnetic pick-up coil without appreciably increasing the diameter of the coil. This object is important since it makes it possible to have a low mean-length-of-turn which allows the resistance of the coil to be kept quite low.

A further object of this invention is to provide a magnetic pick-up wherein the rotor of a distributor carries magnetic means for forming the magnetic path between a flux generating device such as a permanent magnet and the core of a magnetic pick-up coil. In carrying this object forward, the rotor which is formed of insulating material has a depending annular skirt which carries horseshoe shaped magnetic parts that are capable of completing the flux path between the permanent magnet and the core of a pick-up coil.

Still another object of this invention is to provide a magnetic type of pick-up distributor wherein a molded part carries a permanent magnet and a pick-up coil assembly and wherein this molded part is fixed to a vacuum advance plate of the distributor and further wherein a distributor rotor has magnetic inserts for completing the flux path between the permanent magnet and the core of the pick-up coil assembly carried by the molded part. In carrying this object forward, a centrifugal advance mechanism may be provided which is connected between the driving shaft of the distributor and the distributor rotor to adjust the distributor rotor relative to the driving shaft in accordance with the speed of rotation of the shaft.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiment of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a sectional view of a magnetic pick-up made in accordance with this invention.

FIGURE 2 is a sectional view of a magnetic pick-up made in accordance with this invention with the distributor cap removed and illustrating the positioning of the permanent magnet and pick-up coil in a molded part that is carried by the distributor timing plate.

FIGURE 3 is a view similar to FIGURE 2 but illustrating a modified structural arrangement for the permanent magnet and pick-up coil.

Referring now to the drawings and more particularly to FIGURE 1, the reference numeral 10 design-ates the metal base of the magnetic pick-up distributor made in accordance with this invention.

The base 10 carries a bearing sleeve 12 which journals a driving shaft 14. The shaft 14 is suitably driven by the internal combustion engine which has its ignition timing controlled by the magnetic pick-up of this invention. It will be appreciated that the base 10 will have a lower section which can support another sleeve bearing for journalling the shaft 14.

The base 10 supports a conventional distributor cap 16 having a plurality of circumferentially spaced metal inserts 18 which correspond in number to the number of cylinders of the engine. This distributor cap is formed as a molded plastic part and carries the usual center electrode 20 which is connected to the secondary winding of an ignition coil as is well known to those skilled in the art. The distributor cap 16 is attached to the base 10 by any suitable fastening means such as the spring biased hooks 22. p

The magnetic pick-up of this invention includes a timing plate 24 which is connected with a bearing member 26 journalled on the outer portion of the upper end of the sleeve bearing 12. The timing plate 24 is connected with the actuating rod 25 of a conventional vacuum motor generally designated by reference numeral 28. This vacuum motor 28 has the usual spring biased diaphragm 29 which is connected with the rod member that in turn shifts the timing plate 24. It will be appreciated that the timing plate 24 is journalled for rotation around the longitudinal axis of the shaft 14 and when the vacuum unit 28 is connected with a source of vacuum on the engine, the timing plate 24 is adjusted in a manner well known to those skilled in the art. In usual practice, the timing plate 24 is adjusted by vacuum to advance spark timing.

The timing plate 24 carries a pick-up assembly which is generally designated by reference numeral 30. This pick-up assembly 30 is comprised of a one-piece molded part 32 which is formed of a suitable plastic material. The molded part 32 has slots 34, 36, 38 and 40. The slot 38 receives a permanent magnet 42 while the slots 36 and respectively receives soft iron pole tips 44 and 46. The slot 34 receives an iron rod 48 which has a pick-up coil 50 wound thereon. The permanent magnet 42 can take various forms and may be of the ferrite type having a plastic binder.

In fabricating the pick-up coil assembly 30, a molded part is first provided having the required slots for receiving the permanent magnet, the pole tips and the core 48 and coil winding 50. The iron rod 48 is coated with a plastic material which may be applied to this rod by heating the rod to a high temperature and then impinging a finely divided plastic material against the rod whereby the plastic material melts and coats the rod in its entirety. Following this, the coil winding 50 is wound on the rod and the wire that forms this coil winding is coated with a cement which solidifies when the coil winding is heated by passing a current throughthe coil winding for a few seconds. This cement coating eliminates the cost of the coil form or the bobbin and therefore reduces the cost of the coil winding and its core.

After the permanent magnet 42, pole pieces 44 and 46, core 48 and coil winding 50 have been assembled in the slots of the molded plastic part 32, the slots are filled with an epoxy resin or other suitable material to encapsulate these parts and hold them in place. It is apparent that the assembly 30 might be fabricated by other methods.

The assembly 30 is secured to the timing plate 24 by screws 52 which are threaded into the timing plate. The molded plastic part 32 has a central opening 54 which receives the shaft 14 in a manner shown in the drawings.

The magnetic pick-up of this distributor has a rotor which is generally designated by reference numeral 56. This rotor comprises a molded part 58 formed of a suitable plastic material and has an integral annular skirt section 60. The annular skirt section 60 carries a plurality of horseshoe shaped parts 62 which are formed of a magnetic material such as soft iron. These horseshoe shaped parts each have tips 62a and 62b which at times complete a magnetic circuit between the ends of the coil winding core 48 and the ends of the pole tips 44 and 46 as is clearly apparent from FIGURE 2. In the FIGURE 2 position of the rotor, flux will flow from one end of the permanent magnet, for example, the end that engages the pole tip 44, through the pole tip 44, through one of the magnetic inserts 62, through the core 48, through another magnetic insert 62 and then through the pole tip 46 back to an opposite side of the permanent magnet 42. It, of course, will be appreciated that there are times when the magnetic inserts 62 are not aligned with the ends of pole tips 4-4 and 46 and the core 48 whereupon the flux path through the core 48 is broken.

The rotor member 56 is secured to a weight base 64 by one or more fasteners 66. The weight base 64 is driven through a conventional centrifugal advance mechanism generally designated by reference numeral 68. This centrifugal advance mechanism is arranged such that the weight base 64 is adjusted relative to the shaft 14 in accordance with the speed of rotation of the shaft. This centrifugal advance mechanism is of a type shown in the patent to Hartzell et al. 2,872,53 7, and has two flyweights, two springs and a cam plate which is driven by shaft 14 in addition to the weight base 64. This type of centrifugal advance mechanism is also shown in the Short et al. patent, 3,087,001, noted above. The centrifugal advance mechanism is positioned within the plastic molded part 53 in the same manner as shown in the Hartzell et al. patent mentioned above.

The magnetic pick-up of this invention as pointed out above is useful in controlling semiconductor ignition systems of the type shown in the Short et al. patent, 3,087,001. It is to be understood, however, that this magnetic pickup could be used in any type of ignition system wherein pulses of voltage can be used to control a switching function. In addition, the magnetic pick-up can have other uses and in general is useful wherever it is desire-d to control some device by periodically occurring voltage pulses.

When the shaft 14 is rotating, it drives the rotor assembly 56 and the magnetic inserts 62 therefore progressively pass by the ends of the core 48 and the pole tips 44 and 46. In the FIGURE 2 position of the rotor 56, maximum flux will flow through the core 48 and a voltage will be induced in the coil winding 50. As the ends of the magnetic insert 62 move out of alignment with the pole pieces 44 and 46 and the ends of core 48, the flux path for the core 43 is broken and no voltage is induced in the coil winding 50 except for a voltage that may be induced by the collapse of flux. The device of this invention therefore will provide a periodically varying train of voltage pulses, the frequency of which is directly proportional to the speed of the shaft 14. In addition, where this magnetic pick-up is used as a timing device for an ignition system of an internal combustion engine, the device is capable of providing both a vacuum and acentrifugal advance. Thus the occurrence of voltage pulses as related to position of the shaft 14 is adjusted by the centrifugal advance mechanism 68 which adjusts the rotor 56 with respect to the shaft 14 in accordance with the speed of shaft 14. The vacuum advance is obtained by adjusting the timing plate 24} which in turn adjusts the magnetic pick-up assembly 30 relative to the rotor 56 and therefore relative to the magnetic inserts of this rot-or.

The magnetic pick-up of this invention has a number of advantages as compared to those previously used. First of all, by placing the magnetic inserts 62 in the depending annular skirt 60, it is possible to provide a maximum diameter for the working air gaps of the magnetic pick-up. This causes a larger voltage to be induced in the coil winding 50 as compared to previous devices of this type.

Another advantage which is achieved by this invention is the reduction in the resistance of the pick-up coil. This is achieved by reducing the diameter of the coil winding which is made possible by winding it in a long length on the rod 48.

All of the above-noted advantages work to the ultimate result of providing a magnetic pick-up which is better adapted to provide sufficient voltage at low cranking speeds of an engine to adequately time the ignition pulses for the engine.

Referring now to FIGURE 3, a modification of the pick-up assembly 30 is illustrated. In FIGURE 3, the same reference numerals have been used as in FIGURE 1 to identify the same part in each figure. The only difference between FIGURE 3 and FIGURE 2 is that in FIGURE 3 the magnet 42a is longer than the magnet 42 shown in FIGURE 2. In addition, the pole tips 44a and 46a are somewhat shorter in length and are a slightly different configuration at their ends. The core 48a in FIGURE 3, has a slightly different configuration at its ends as can be seen by a comparison of FIGURES 2 and 3.

The FIGURE 3 embodiment operates in the same manner as that shown in FIGURES 1 and 2 and is an alterna tive arrangement for construction of the magnetic pick-up assembly 30.

While the embodiments of the present invention as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A voltage generating device comprising, first and second relatively rotatable parts, a permanent magnet carried by said first part, first and second magnetic members carried by said first part located in a magnetic circuit with said permanent magnet and terminating in first and second pole tips, a core member formed of magnetic material carried by said first part, said core member terminating in third and fourth pole tips, a coil winding wound on said core member, and magnetic means carried by said second part aligned with said pole tips for completing and interrupting magnetic circuits between said first and fourth and said second and third pole tips of said first part.

2. An ignition timing control device comprising, a cap member of insulating material having a center electrode and a plurality of circumferentially spaced electrodes, a rotor member of insulating material carrying contact means which progressively connect the center electrode of said cap member with said circumferentially spaced electrodes when said rotor member rotates, a pick-up coil, a source of flux, and a magnetic circuit magnetically coupling said source of flux and said pick-up coil, said magnetic circuit including at least one magnetic part carried directly by the insulating material of said rotor member.

3. An ignition timing device comprising, a cap member of insulating material having a center electrode and a plurality of circumferentially spaced outer electrodes, a rotor part of insulating material, said rotor part carrying contact means which connects the center electrode with said outer electrodes of said cap as said rotor part rotates, a pick-up coil, a source of flux, and a magnetic circuit coupling said pick-up coil and said source of flux, said magnetic circuit including inserts of magnetic material carried by said rotor part.

4 An ignition timing control device comprising, a part of insulating material, a permanent magnet carried by said part, a coil winding wound on a core member carried by said part, a rotor member of insulating material carrying a contact means for transferring ignition pulses to a plurality of spark plugs, and magnetic inserts in said rotor member positioned to periodically complete a mag netic circuit between said permanent magnet and said core.

5. An ignition control device comprising, a base member, a distributor cap having electrical inserts carried by said base member, a shaft rotatably mounted in said base member, a support, a permanent magnet, a core member and a coil winding each carried by said support, said core member and coil winding being magnetically coupled, a rotor member of insulating material having electrical contact means for electrically connecting the electrical inserts of said distributor cap, and magnetic means embedded in said rotor member positioned to periodically complete a magnetic circuit between said magnet and core member carried by said support.

6. The ignition timing device according to claim 5 wherein a centrifugal advance mechanism drives said rotor member from said shaft.

7. The ignition timing device according to claim 5 wherein the support which carries the permanent magnet and coil winding is secured to a timing plate which is adjusted by a vacuum unit.

8. A voltage generating device comprising, first and second relatively rotatable plastic parts, a permanent magnet, a core and a coil winding each disposed within the plastic material of said first part, said coil winding being magnetically coupled to said core, said core terminating in a first pair of pole tips, a second pair of pole tips magnetically connected to opposite ends of said permanent magnet disposed within the plastic material of said first part, and means formed of magnetic material carried by said second plastic part and located adjacent said pole tips for periodically completing a magnetic circuit between ends of said first and second pairs of pole tips.

9. The Voltage generating means according to claim 8 wherein the core and coil winding are encapsulated in said first plastic part and wherein said permanent magnet and pole tips are encapsulated in said first plastic part.

10. An ignition control device comprising, a base member, a distributor cap of insulating material carried by said base member having conductive inserts, a shaft journalled for rotation in said base member, a pick-up assembly including a support member, a permanent magnet, a core member and coil winding each carried by said support member, a timing plate, means securing said pick-up assembly to said timing plate, a vacuum unit including an actuator connected to said timing plate, a rotor mem ber including a body member of insulating material, said body member carrying electrical contact means which periodically connect the conductive inserts of said distributor cap, centrifugal advance mechanism interconnecting said shaft and said rotor member, and a plurality of generally U-shaped magnetic inserts carried by said body member adjacent said pick-up assembly for periodically completing a magnetic circuit between said permanent magnet and said core member.

11. A voltage generating device comprising, first and second relatively rotatable parts, a first magnetic circuit branch carried by and extending transversely across said first part terminating in first and second pole tips located at opposite ends of said first magnetic circuit, a second magnetic circuit branch carried by and extending transversely across said first part terminating in third and fourth pole tips located at opposite ends of said second magnetic circuit branch, said first pole tip being spaced from said third pole tip and said second pole tip being spaced from said fourth pole tip, said first and second magnetic circuit branches being comprised of a permanent magnet and a magnetic core carrying a coil winding, and a pair of magnetic means located on opposite sides of said second part, said magnetic means in one position of said parts magnetically connecting respectively said first and third pole tips and said second and fourth pole tips, said parts in another position disconnecting said pole tips.

12. A voltage generating device comprising, first and second relatively rotatable parts, first and second magnetic circuit branches carried by said first part terminating respectively in first and second and third and fourth pole tips, said first and third pole tips being spaced from each other and located at one side of said first part, said second and fourth pole tips being spaced from each other and located at an opposite sideof said first part, said magnetic circuit branches including a flux generating means and a coil winding, and a pair of magnetic means carried by said second part aligned with said pole tips and operative upon relative rotation of said first and second parts to complete and interrupt a flux path between said first and third and second and fourth pole tips.

13. A rotor member for a voltage pulse generator type of distributor comprising, a body section of insulating material, said body section carrying electrical contact means which are adapted to connect the center electrode and outer circumferentially spaced electrodes of a distributor cap, and a plurality of circumferentially spaced generally U-shaped magnetic parts carried by said body section.

14. A rotor member for a voltage pulse generating type of distributor comprising, a body member formed of insulating material, said body member carrying electrical contact means which are adapted to connect the center electrode and outer circumferentially spaced electrodes of a distributor cap, and a plurality of circumferentially spaced magnetic segments embedded in said body member and carried thereby. 

14. A ROTOR MEMBER FOR A VOLTAGE PULSE GENERATING TYPE OF DISTRIBUTOR COMPRISING, A BODY MEMBER CARRYING ELECTRICAL SULATING MATERIAL, SAID BODY MEMBER CARRYING ELECTRICAL CONTACT MEANS WHICH ARE ADAPTED TO CONNECT THE CENTER ELECTRODE AND OUTER CIRCUMFERENTIALLY SPACED ELECTRODES OF A DISTRIBUTOR CAP, AND A PLURALITY OF CIRCUMFERENTIALLY SPACED MAGNETIC SEGMENTS EMBEDDED IN SAID BODY MEMBER AND CARRIED THEREBY. 